Chongqing, China, 23 Dec., 2003 R.A. Hawrelak CBE 497 CBE 317

The Incident Rupture of natural gas well kills scores in China. A toxic gas cloud of CH4 and H2S covered an area roughly 4 km wide by 6 km long. The cloud spewed CH4 and H2S 30m high into the air.

Results 233 people killed. 64,000 forced to flee their homes. 9,000 people hospitalized. Thousands of dead animals including –2,275 rabbits –866 pigs –241 ducks –476 chickens –38 dogs

Reasons for Incident A series of missteps by workers and negligence by gas field developers triggered a toxic cloud that spewed natural gas with a high concentration of H2S. Gas drilling rigs usually have ‘blow-out preventers’ installed in the drilling pipe. It is not known at this time if the well developers used this common safety device.

Mitigation 24 hours after the incident started, disaster workers ignited the gas streaming from the well head to burn away the toxic fumes. They attempted to plug the well with 260 cu.m. of cement and earth moving equipment. However, there are no reports that this was successful.

H2S Toxicity

Typical Dispersion Results

Lessons Learned No Emergency Warning system in place. No Emergency Evacuation plan in place. Workers were unsure of emergency procedures. Hospitals were poorly equipped to handle all the injured.

End of Presentation There will be questions on the final exam relating to toxic gas incidents.